Today's Message Index:
----------------------
1. 03:46 AM - Avionics Master switch (tomcostanza)
2. 06:40 AM - Re: B&C alt voltage goes right up to 16V (user9253)
3. 07:19 AM - Re: B&C alt voltage goes right up to 16V (user9253)
4. 11:49 AM - testing of backup alternator (Erich_Weaver@urscorp.com)
5. 09:38 PM - Re: Avionics Master switch (Robert L. Nuckolls, III)
6. 09:38 PM - Re: B&C alt voltage goes right up to 16V (Robert L. Nuckolls, III)
7. 09:41 PM - Re: Re: New operations model for the AeroElectric Connection (Robert L. Nuckolls, III)
8. 09:51 PM - Re: Re: B&C alt voltage goes right up to 16V (Robert L. Nuckolls, III)
9. 09:56 PM - Re: testing of backup alternator (Robert L. Nuckolls, III)
Message 1
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| Subject: | Avionics Master switch |
Before everyone yawns and says, "Not another question about avionics master switches",
I'll ask you to indulge me.
Suppose I had a "friend", who was paranoid about blowing-up his $10,000 WAAS gps,
and $20,000 glass panel, and hadn't read Bob's epistles about fault tolerance
specs, etc. But this "friend" didn't want the single point failure of an avionics
master switch. Suppose also, that he had a progressive master switch
(Off - Batt only/alternator field off - On/alternator field on). Why couldn't
this "friend" shut down by turning off the master switch before shutting down
the engine? Is this the bugaboo that the non-Aeroelectric crowd fears? ie.
Is the sudden collapse of the alternator field the culprit everyone fears, or
is it the limbo-like state of the alternator as the engine rpm winds down after
pulling the mixture they fear? Would this procedure raise more concerns than
it eased?
I once had an instructor that shut off the alternator field and looked for a hiccup
on the ammeter as part of a pre-takeoff check (avionics on at this point).
This was the same instructor that "enlightened" me about the reason for shutting
off all avionics before starting and before shutting down the engine.
--------
Clear Skies,
Tom Costanza
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=309853#309853
Message 2
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| Subject: | Re: B&C alt voltage goes right up to 16V |
You confirmed that there is indeed an over-voltage condition. The voltage regulator
is not doing its job, for whatever reason. The rain may or may not be a
factor. Perhaps the regulator got too hot at some point. If you can not adjust
the output voltage to within normal range, then the voltage regulator should
be replaced.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=309876#309876
Message 3
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| Subject: | Re: B&C alt voltage goes right up to 16V |
There is another possibility, depending on where in the circuit the voltage regulator
measures the voltage. If there is a high resistance in the field circuit,
the regulator might be seeing a lower voltage than is at the main bus. In
that case, the regulator would tell the alternator to put out more. Make sure
that all of the connections in the electrical system are secure, especially
in the regulator sense and field circuits.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=309881#309881
Message 4
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| Subject: | testing of backup alternator |
Bob, your recently responded to a couple of posts from Jared Yates, who
was
asking (in part) about testing of the backup alternator in a Z-13/8 sys
tem.
Cant speak for Jared, but Im not sure his real question was effectively
answered and I am interested in this as well,, so thought I would follo
w
up. How do I go about assuring myself that my SD-8 will work as advert
ised
when called upon? Can I just turn off the master, flip on the switches
for
the SD-8 and the e-bus alternate feed, and wait to see if I get a low
voltage warning light on my engine monitor? Can I do this on the groun
d at
idle, or do I need to have the RPM elevated? Feeling a bit boneheaded
about this, but would be more boneheaded to not ask, and find out later
my
SD-8 was providing no backup at all.
thanks for your service
Erich Weaver
Message 5
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| Subject: | Re: Avionics Master switch |
At 05:45 AM 8/23/2010, you wrote:
><Tom@CostanzaAndAssociates.com>
>
>Before everyone yawns and says, "Not another question about avionics
>master switches", I'll ask you to indulge me.
>
>Suppose I had a "friend", who was paranoid about blowing-up his
>$10,000 WAAS gps, and $20,000 glass panel, and hadn't read Bob's
>epistles about fault tolerance specs, etc. But this "friend" didn't
>want the single point failure of an avionics master switch. Suppose
>also, that he had a progressive master switch (Off - Batt
>only/alternator field off - On/alternator field on). Why couldn't
>this "friend" shut down by turning off the master switch before
>shutting down the engine? Is this the bugaboo that the
>non-Aeroelectric crowd fears? ie. Is the sudden collapse of the
>alternator field the culprit everyone fears, or is it the limbo-like
>state of the alternator as the engine rpm winds down after pulling
>the mixture they fear? Would this procedure raise more concerns than it eased?
No, the #1 "radio killer" is supposed to be the starter.
Have you read?
http://aeroelectric.com/articles/avmaster.pdf
If one really wants an Avionics Master, it's
easily added in series with the normal feed-path
diode without major impact to failure mode effects
analysis.
There are but four energy sources that the designer
needs to consider when configuring the electrical
system.
(1) Battery: Limited total energy but capable
of great current due to low internal impedance.
(2) Engine Driven Power: Usually an alternator
capable of great total energy but current limited
due magnetics and internal impedances.
(3) Direct Lightning Strikes: Most light aircraft
designers don't strive for resistance to lightning
strokes. Lots of current, arcing, but again, not
as much energy in the stroke as your alternator puts
out in twenty minutes or so or the battery can deliver
in a complete dumping of charge.
(4) All other reactive sources are low energy,
short duration events, routinely trapped off as
a matter of design and qualification.
Risks from battery and alternator faults have
been easily managed by proper wire sizes, fuse/breaker
sizes, ov-protection on the alternator. Legacy
design goals call for designing to expect, withstand
and make graceful recovery from events that lie within
this envelope
http://www.aeroelectric.com/Pictures/Curves/MSTD704_28V_Trans.jpg
I can tell you that starting the engine does not
exceed this recommendation.
We also limit abnormal events to this envelope
http://www.aeroelectric.com/Pictures/Curves/MSTD704_28V_OV.jpg
. . . which is no big deal.
>I once had an instructor that shut off the alternator field and
>looked for a hiccup on the ammeter as part of a pre-takeoff check
>(avionics on at this point). This was the same instructor that
>"enlightened" me about the reason for shutting off all avionics
>before starting and before shutting down the engine.
He was simply repeating the mantra handed down to
him by his teachers. I have gone on spike hunting
expeditions on airplanes from C-150 to BeechJets
and failed to see anything that exceeded the design
goal limits . . . in fact, aside from starter inrush
brownout . . .
http://www.aeroelectric.com/Pictures/Curves/99_Saturn_SL1_2.gif
http://www.aeroelectric.com/Pictures/Curves/99_Saturn_SL1.jpg
http://www.aeroelectric.com/Pictures/Curves/95_GMC_Safari_3.gif
http://www.aeroelectric.com/Pictures/Curves/95_GMC_Safari_1.gif
http://www.aeroelectric.com/Pictures/Curves/turbine_start_a.jpg
The rest of the things you see on the bus are exceedingly
un-exciting.
http://www.aeroelectric.com/Pictures/Curves/Safari_Bus_Noise_1.gif
http://www.aeroelectric.com/Pictures/Curves/Safari_Bus_Noise_2.gif
Bob . . .
Message 6
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| Subject: | Re: B&C alt voltage goes right up to 16V |
At 10:23 PM 8/22/2010, you wrote:
>
>I installed a b&c alt on an o200 with the PMR1C-14. After about 10
>hrs on it with no problems one morning, after the airplane sat out
>in the rain, the voltage started going right up to 16V at takeoff
>power tripping the crowbar OV protection. I have not played with the
>setpoint since it was working fine at the beginning (stayed just
>under 14v) so it should not have changed. I can't see that water got
>into the regulator as it is potted in epoxy or similar. My battery
>acts fine, takes a charge in a reasonable amount of time and my volt
>meter is correct as I checked it with another and the crowbar goes
>off and just the right voltage. What could cause this?
Only a failure within the PMR1C-14. Suggest you
return it to B&C for a checkup.
Bob . . .
Message 7
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| Subject: | Re: New operations model for the AeroElectric |
Connection
At 10:17 PM 8/22/2010, you wrote:
>All I can do is offer to return the favor, Bob, if you ever need any
>machine work for a project, I'd be happy to help.
Do you have a mill with a digital readout?
> My little Kolb continues to fly along with zero electrical issues.
> Security like that is absolutely priceless, IMHO.
Great news!
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 8
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| Subject: | Re: B&C alt voltage goes right up to 16V |
At 09:19 AM 8/23/2010, you wrote:
>
>There is another possibility, depending on where in the circuit the
>voltage regulator measures the voltage. If there is a high
>resistance in the field circuit, the regulator might be seeing a
>lower voltage than is at the main bus. In that case, the regulator
>would tell the alternator to put out more. Make sure that all of
>the connections in the electrical system are secure, especially in
>the regulator sense and field circuits.
The PMR1C-14 is a more robust version of the
rectifier/regulators supplied with the majority
of 20A or smaller PM alternators. VERY simple,
and senses voltage right at the output lead of
the regulator.
If this particular regulator is misbehaving, it's
unlikely that the problem lies outside the device.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 9
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| Subject: | Re: testing of backup alternator |
At 01:46 PM 8/23/2010, you wrote:
>Bob, your recently responded to a couple of posts from Jared Yates,
>who was asking (in part) about testing of the backup alternator in a
>Z-13/8 system. Cant speak for Jared, but Im not sure his real
>question was effectively answered and I am interested in this as
>well,, so thought I would follow up. How do I go about assuring
>myself that my SD-8 will work as advertised when called upon? Can I
>just turn off the master, flip on the switches for the SD-8 and the
>e-bus alternate feed, and wait to see if I get a low voltage warning
>light on my engine monitor? Can I do this on the ground at idle, or
>do I need to have the RPM elevated? Feeling a bit boneheaded about
>this, but would be more boneheaded to not ask, and find out later my
>SD-8 was providing no backup at all.
You can turn alternators on/off at any time under
any conditions without regard to system safety
or hazard to other components.
The SD-8 does need a lot of RPM to produce full
output. I doubt that you want to run a full-throttle
preflight. During mag test you can turn the main
alternator off and the SD-8 on. If the loadmeter
shows ANY significant output, the alternator is
probably fine even if low voltage warnings continue
and the SD-8 output is less than 8-10 amps that you
can expect at cruise.
You can also wait until airborne and go to the SD-8 supported
E-bus mode to test the system under more realistic conditions
before you get too far from home.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
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